JP2014211342A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor for reducing a transmitted strain when the pressure sensor is attached to a fitting member and having an improved accuracy of pressure detection.SOLUTION: In order to achieve the above objective, the present invention is configured to have a cylindrical container 33 having a bottom face 31 and a side face 32 extending in the height direction, and a strain detection element 37 provided on the bottom face 31 or the side face 32. The container 33 has an engagement part 35 provided on the opposite side to the bottom face 31 and a flange 38 provided between the engagement part 35 and the strain detection element 37. The flange 38 has a first portion 39 in contact with the side face 32 and a second portion 40 located on the outside of the first portion 39, a first height from the bottom face 31 to the first portion 39 being higher than a second height from the bottom face 31 to the second portion 40.

Description

  The present invention relates to a pressure sensor used for various control devices, automobile engine control, suspension control, and the like.

  Conventional pressure sensors of this type are configured as shown in FIGS.

  Hereinafter, a conventional pressure sensor will be described with reference to the drawings.

  6 is a perspective view of a conventional pressure sensor, FIG. 7 is a side sectional view of the conventional pressure sensor, and FIG. 8 is a top view of the conventional pressure sensor.

  As shown in FIGS. 6 to 8, the conventional pressure sensor has a container 1 made of SUS630. The container 1 is provided with a cylindrical portion 3 provided with a hollow hole 2 inside, and a flat plate portion 4 that closes an upper portion of the hollow hole 2 in the cylindrical portion 3. Further, a flange 5 is provided on the cylindrical portion 3 of the container 1 so as to protrude outward, and a notch 6 is provided at substantially the center of the flange 5 over the entire circumference. A strain detecting element 7 is adhered to the upper surface of the container 1, and a first vibrator 8 made of a both-end supported beam is provided above the flat plate portion 4. On the top surface of the first vibrator 8, a first drive unit 9 and a first detection unit 10 configured by stacking Pt, PZT, and Au are provided. Further, the strain detecting element 7 is provided with a second vibrator 11 which is located above the cylindrical portion 3 and is formed of a both-end supported beam. On the upper surface of the second vibrator 11, a second driving unit 12 and a second detection unit 13 configured by stacking Pt, PZT, and Au are provided. In addition, the strain detection element 7 is provided with a wiring pattern 14 made of Au. The wiring pattern 14 includes the first drive unit 9 and the first detection unit 10 in the first vibrator 8, and The second vibrator 11 is electrically connected to the second drive unit 12 and the second detection unit 13. The strain detection element 7 is provided with a processing circuit 15 made of an IC. The processing circuit 15 is connected to the first drive unit 9 and the second vibrator 11 in the first vibrator 8 via the wiring pattern 14. A drive signal is input to the second drive unit 12 in FIG. 5 to drive the first vibrator 8 and the second vibrator 11 in vibration, and the first detection unit 10 and the second vibrator in the first vibrator 8. The natural frequency of the first vibrator 8 and the second vibrator 11 is detected by processing the output signal from the second detector 13 in the vibrator 11.

  In such a conventional pressure sensor, there is a problem that the strain detection accuracy is lowered by transmitting the strain generated when attached to the mounting member to the strain detection element. On the other hand, as shown in FIG. 9, the conventional pressure sensor 20 protrudes outward from the cylindrical portion 23 in the container 21 having the flat plate portion 24 provided with the first vibrator 8 and the second vibrator 11. In addition, a flange 25 is provided, and a groove 26 is provided in the flange 25 over the entire circumference. According to this configuration, the flange 25 is provided so as to protrude outward from the cylindrical portion 23, and the groove 26 is provided in the flange 25, so that it occurs when the pressure sensor is attached to the mating attachment member 28. It is possible to prevent the stress from being transmitted to the first vibrator 8 and the second vibrator 11, so that only the pressure of the liquid 29 to be detected filled in the hollow hole 22 is caused by the first vibrator 8. It is configured to detect. In addition, since the stepped portion 27 is provided in the flange 25, the flange is deformed in two steps around the end portion 18 of the stepped portion 27 and the apex 19 of the groove 26. As a result, the pressure sensor is attached to the counterpart mounting member 28. In order to further absorb the stress generated when attaching to the hollow member 22, only the pressure of the liquid 29 to be detected filled in the hollow hole 22 is detected by the first vibrator 8 (Patent Document 1).

JP 2012-118057 A

  However, the pressure sensor having the above-described conventional configuration disclosed in Patent Document 1 is configured to absorb the stress generated when the pressure sensor is attached to the mounting member by providing a flange or a stepped portion. However, stress is generated by attaching the pressure sensor to the mounting member, and the strain is transmitted to the strain detecting element.

  Therefore, an object of the present invention is to provide a pressure sensor that further reduces transmission distortion when a pressure sensor is attached to a mounting member, and improves pressure detection accuracy.

  In order to solve the above problems, the present invention has a cylindrical container having a bottom surface and a side surface extending in the height direction, and a strain detection element provided on the bottom surface or the side surface, A fitting portion provided on the opposite side of the bottom surface; and a flange provided between the fitting portion and the strain detection element, wherein the flange is in contact with the first portion and the first portion. A second portion located outside the portion, wherein a first height from the bottom surface to the first portion is higher than a second height from the bottom surface to the second portion. .

  With the above configuration, the present invention attaches the pressure sensor to the mounting member by making the height from the bottom surface of the container to the first portion of the flange higher than the height from the bottom surface of the container to the second portion of the flange. Since the strain transmitted to the strain detection element can be reduced, the detection accuracy of the pressure sensor can be improved.

The perspective view of the pressure sensor of one embodiment of the present invention Side sectional view of the same pressure sensor Side view of the pressure sensor (A) Side sectional view at the time of press-fitting of the same pressure sensor, (b) Side sectional view after press-fitting of the same pressure sensor. Perspective view of the same pressure sensor A perspective view of a conventional pressure sensor Side sectional view of a conventional pressure sensor Top view of conventional pressure sensor Side sectional view of a conventional pressure sensor

  An embodiment of the present invention will be described with reference to the drawings. In the embodiment of the present invention, components having the same configuration are denoted by the same reference numerals.

  FIG. 1 is a perspective view of a pressure sensor 30 according to an embodiment of the present invention, FIG. 2 is a side sectional view of the pressure sensor 30, and FIG. 3 is a side view of the pressure sensor 30.

  As shown in FIGS. 1, 2, and 3, a pressure sensor 30 according to an embodiment of the present invention is made of a material such as metal or plastic, and has a bottom surface 31 and a side surface extending in the height direction (Y-axis direction). A container 33 having 32 is provided. The container 33 is provided with a thick portion 34 on the side surface 32 that is thicker than the side surface 32 in the direction substantially orthogonal to the Y-axis direction (X-axis direction), and a part of the thick portion 34 extends in the Y-axis direction. An existing flat portion 36 is provided, and the flat portion 36 is provided with a strain detection element 37 that detects strain generated in the container 33. The container 33 has a fitting portion 35 on the opposite side of the bottom surface 31, and a flange 38 is provided between the fitting portion 35 and the strain detection element 37. The flange 38 is in contact with the side surface 32. A portion 39; a second portion 40 located outside the first portion 39 in the X-axis direction; and a third portion 41 located outside the second portion 40 in the X-axis direction. The first height L1 from the bottom surface to the first portion 39 is higher than the second height L2 from the bottom surface 31 to the second portion 40, and is the second height from the bottom surface 31 to the second portion 40. The height L <b> 2 is lower than the third height L <b> 3 from the bottom surface 31 to the third portion 41.

  The strain detecting element 37 is provided with a first vibrator 42 made of a both-end supported beam extending in the X-axis direction. A first drive unit 43 and a first detection unit 44 configured by stacking Pt, PZT, and Au are provided on the upper surface of the first vibrator 42. Further, the strain detecting element 37 is provided with a second vibrator 45 made of a both-end support beam in the Y-axis direction, and Pt, PZT, and Au are laminated on the upper surface of the second vibrator 45. A second drive unit 46 and a second detection unit 47 are provided. The strain detection element 37 is provided with a wiring pattern 48 made of Au. The wiring pattern 48 includes the first drive unit 43 and the first detection unit 44 in the first vibrator 42, and The second vibrator 45 is electrically connected to the second drive unit 46 and the second detection unit 47. The strain detection element 37 is provided with a processing circuit 49 made of an IC. The processing circuit 49 is connected to the first drive unit 43 and the second vibrator 45 in the first vibrator 42 via a wiring pattern 48. A drive signal is input to the second drive unit 46 in FIG. 6 to drive the first vibrator 42 and the second vibrator 45 in vibration, and the first detection unit 44 and the second vibrator 42 in the first vibrator 42. The natural frequency of the first vibrator 42 and the second vibrator 45 is detected by processing the output signal from the second detection unit 47 of the vibrator 45.

  Next, the operation of the pressure sensor 30 according to the first embodiment of the present invention configured as described above will be described.

  An alternating voltage having substantially the same frequency as the natural frequency fa of the first vibrator 42 is applied from the processing circuit 49 to the first drive unit 43 of the first vibrator 42, and in the second vibrator 45. An AC voltage having substantially the same frequency as the natural frequency fb of the second vibrator 45 is applied to the second driving unit 46. Then, the first vibrator 42 performs string vibration at the natural frequency fa, and the second vibrator 45 performs string vibration at the natural frequency fb. In this state, when the output signal from the first detection unit 44 in the first vibrator 42 is processed by the processing circuit 49, the frequency fa is detected. Similarly, the second detection unit in the second vibrator 45 is detected. From 47, the frequency fb is detected.

  The pressure sensor 30 is filled with the liquid to be detected, and when the pressure of the liquid to be detected rises, the container 33 is distorted toward the outside. At this time, the flat surface 36 provided with the strain detection element 37 bulges outward, and a tensile load acts on the strain detection element 37. Thereby, since the frequency fa of the first vibrator 42 in the strain detecting element 37 is increased, the processing circuit 49 processes the output signal from the first detection unit 44 of the first vibrator 42. As the amount of change in frequency, the pressure of the liquid to be detected filled in the container 33 can be detected.

  Similarly to the first vibrator 42, the frequency fb of the second vibrator 45 is a tensile force that acts on the strain detection element 37 when the pressure of the liquid to be detected filled in the container 33 rises. The frequency fb of the second vibrator 45 increases according to the load. Therefore, by processing the output signal from the second detection unit 47 of the second vibrator 45 by the processing circuit 49, the pressure of the liquid to be detected filled in the container 33 is detected as the amount of change in frequency. Can do.

  Here, considering the case where the temperature around the pressure sensor 30 changes and the natural frequency of the first vibrator 42 changes, the pressure sensor 30 according to the embodiment of the present invention has the second vibration. By detecting a change in the natural frequency of the child 45, a temperature change around the pressure sensor 30 can be detected. For this reason, it has the effect of being able to correct | amend the variation | change_quantity of the output signal which generate | occur | produces with a temperature change from the output signal value according to the pressure detected from the 1st vibrator | oscillator 42. FIG.

  Next, a method for assembling the pressure sensor 30 according to one embodiment of the present invention and the effects thereof will be described with reference to the drawings.

  First, the container 33 prepares a bar (not shown) and cuts the bar (not shown) to form a hollow hole and a flat portion 36 in the container 33.

  Next, the strain detection element 37 deposits a wiring pattern 48 made of Au on the upper surface of a semiconductor substrate (not shown), and then the first drive unit 43 and the first detection unit of the first vibrator 42. 44 and Pt are vapor-deposited at locations where the second drive unit 46 and the second detection unit 47 of the second vibrator 45 are provided.

  Next, PZT is vapor-deposited on the upper surface of Pt, and then Au is vapor-deposited to form the first drive unit 43 and the first detection unit 44 on the upper surface of the first vibrator 42, and at the same time, the second vibrator 45. A second drive unit 46 and a second detection unit 47 are formed on the upper surface of the substrate.

  Next, a processing circuit 49 made of an IC is placed on the upper surface of a semiconductor substrate (not shown), and the processing circuit 49 is placed in the first drive unit 43, the first detection unit 44, and the first vibrator 42. The strain detection element 37 is formed by electrically connecting the second drive unit 46 and the second detection unit 47 of the second vibrator 45 to the wiring pattern 48.

  Finally, the pressure sensor 30 is formed by sticking the strain detection element 37 to the flat portion 36 of the container 33.

  4A and 4B show the stress applied to the pressure sensor 30 during press-fitting. 4A is a side sectional view of the pressure sensor 30 at the time of press-fitting, and FIG. 4B is a side sectional view of the pressure sensor after the press-fitting. The pressure sensor 30 assembled as described above is press-fitted into a mounting member 51 provided with a hole 50.

  In the pressure sensor 30, stress F as shown in FIGS. 4A and 4B is applied to the container 33 during and after press-fitting. As shown in FIG. 4A, when the pressure sensor 30 for press-fitting the fitting portion 35 into the hole 50 is applied, a stress f1 is applied to the fitting portion 35 in the Y-axis direction by the stress F, and this stress f1 is applied to the flange. 38 is transmitted, and a stress f <b> 2 is generated outward with respect to the side surface 32. In addition, after the pressure sensor 30 is press-fitted into the mounting member 51, stress f <b> 3 is applied from the mounting member 51 toward the inside of the fitting portion 35 with respect to the fitting portion 35, as shown in FIG. The stress f3 is transmitted through the flange 38, and the stress f4 applied to the side surface 32 toward the outside is generated.

  As described above, when the stresses f2 and f4 are applied to the side surface 32, the stresses f2 and f4 are transmitted from the base point 52 to the side surface 32 and the flat portion 36 provided with the strain detection element 37 is deformed. Since 37 is always in a state of being distorted, the pressure detection accuracy of the pressure sensor 30 is lowered.

  Here, in the pressure sensor 30 according to the embodiment of the present invention, the first height L1 from the bottom surface 31 to the first portion 39 is set higher than the second height L2 from the bottom surface to the second portion 40. By adopting a configuration in which the distance L is high, the distance from the strain detection element 37 to the base point 52 is increased by the distance L compared to a conventional pressure sensor having the same first height and second height as shown in FIG. . As a result, the pressure sensor 30 according to the embodiment of the present invention can suppress the transmission of strain to the strain detection element 37 by a distance L as compared with the conventional pressure sensor.

  In the pressure sensor 30 according to the embodiment of the present invention, the second height L2 from the bottom surface 31 to the second portion 40 is greater than the third height L3 from the bottom surface 31 to the third portion 41. Since the rigidity of the second portion 40 of the flange 38 is higher than the rigidity of the third portion 41 of the flange 38 due to the reduction, the stresses f1 and f3 are transmitted to the flange 38 when the stresses f1 and f3 are transmitted. Due to the difference in rigidity between the portion 40 and the third portion 41, stress is applied to the second portion 40 toward the outside. Thereby, since the transmission stress to the base point 52 is absorbed by the second portion 40, the stresses f2 and f4 applied to the base point 52 are reduced. For this reason, it is possible to reduce transmission distortion to the strain detection element 37 when the pressure sensor 30 is press-fitted into the mounting member 51.

  Further, when the stress applied to the strain detecting element 37 in one embodiment of the present invention was measured, it was reduced by 95.5% with respect to the stress applied to the strain detecting element in the conventional structure. It was confirmed that the distortion transmitted to the strain detecting element 37 could be reduced depending on the form.

  Further, in one embodiment of the present invention, the pressure sensor 30 includes the thick portion 34, and the flat portion 36 is formed on the thick portion to mount the element, thereby making it easy to attach the pressure sensor 30. Furthermore, since the cutting amount can be reduced, the pressure sensor 30 can be assembled at a lower cost.

  Further, as shown in FIG. 5, a thick portion 34 may be provided between the strain detection element 37 and the flange 38. By adopting such a configuration, since the transmission strain is transmitted through the surface of the container 33, the distance from the base point to the strain detection element 37 can be increased, so that the transmission strain can be further reduced.

  In the embodiment of the present invention, the strain detection element 37 is provided on the flat portion 36, but may be provided on the bottom surface 31.

  The pressure sensor of the present invention has an effect that the processing accuracy of the pressure sensor having high sensitivity and improved characteristics can be improved, and therefore, the pressure sensor used for various control devices, automobile engine control, suspension control, etc. Useful in.

30 Pressure sensor 31 Bottom surface 32 Side surface 33 Container 34 Thick part 35 Fitting part 36 Flat part 37 Strain detecting element 38 Flange 39 First part 40 Second part 41 Third part 42 First vibrator 43 First Drive unit 44 first detection unit 45 second vibrator 46 second drive unit 47 second detection unit 48 wiring pattern 49 processing circuit 50 hole 51 mounting member 52 base point

Claims (7)

A cylindrical container having a bottom surface and a side surface extending in the height direction;
A strain detecting element for detecting pressure applied to the container provided on the bottom surface or the side surface;
The container has a fitting portion provided on the opposite side of the bottom surface, and a flange provided between the fitting portion and the strain detection element,
The flange has a first portion in contact with the side surface and a second portion located outside the first portion;
The pressure sensor according to claim 1, wherein a first height from the bottom surface to the first portion is higher than a second height from the bottom surface to the second portion. The flange has a third portion located outside the second portion;
2. The pressure sensor according to claim 1, wherein a third height from the bottom surface to the third portion is higher than the second height. The side surface has a thick part and a thin part,
The pressure sensor according to claim 1, wherein a thickness of the thin portion in a direction orthogonal to the height direction is smaller than a thickness of the thick portion. The pressure sensor according to claim 3, wherein the thick portion is provided between the strain detection element and the flange. The strain detecting element is
A first vibrator;
A first drive unit for driving the first vibrator;
The pressure sensor according to claim 1, further comprising a first detection unit that outputs a signal corresponding to a change in the natural frequency of the first vibrator. The strain detecting element is
A second vibrator;
A second drive unit for driving the second vibrator;
A second detector that outputs a signal according to a change in the natural frequency of the second vibrator;
The pressure sensor according to claim 1, wherein the second vibrator is formed in a direction substantially orthogonal to the first vibrator. The strain detecting element is
A processing circuit that detects a change in the vibration frequency of the vibrator based on signals output from the first detection unit and the second detection unit;
The pressure sensor according to claim 6, wherein distortion is detected based on a detection result of the processing circuit.

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